After running the half marathon, Keith Hagler, cheers on runners while along Allen Pkwy on the 24th mile during the Chevron Houston Marathon Sunday, Jan. 30, 2011, in Houston. About 22,000 runners participated

Costumed spectators cheer on runners around Mile 13 along University Blvd. in West University during the Chevron Houston Marathon Sunday, Jan. 17, 2010. ( Melissa Phillip / Chronicle )

Costumed spectators cheer on runners around Mile 13 along University Blvd. in West University during the Chevron Houston Marathon Sunday, Jan. 17, 2010. ( Melissa Phillip / Chronicle )

Photo: Melissa Phillip, Staff

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Possible thunderstorms would affect Houston Marathon

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Runners in Houston's Marathon may be expecting cold temperatures and a probability of rain, but if lightning and thunderstorms roll through the area Sunday morning, the race could be canceled for the first time in its history.

Meteorologist Kent Prochazka said earlier Wednesday a cold front and precipitation coming through this weekend could produce lightning during Sunday's race.

Houston Marathon spokeswoman Vicky Oddi said the cancellation policy depends on whether conditions present a danger to participants, which lightning does. Marathon organizers have been working with Houston's Office of Emergency Management, which has not warned of lightning or severe weather.

The race's policy states that if severe thunderstorms with the threat of lightning are forecast to go throughout the event, cancellation is possible.

The marathon has never started late or been canceled in its 41-year history.

Oddi said the cap for race participation is 25,000 and 24,000 have signed up so far. If the race is canceled, the next event will be in 2014.

Postponing the race is also possible if severe weather develops, but that would be a "game day decision," depending on when the weather would clear, Oddi said.

Organizers do not cancel in advance for thunderstorms and rain will not stop the race.

She said race organizers have not begun talking about the possibility of postponing or cancelling the race because they have not noticed severe weather in the forecast.

"If it is raining Sunday morning and there has been no lightning, we won't cancel before the start of the race," Oddi said. "If the issue is lightning, the determination would be a game day decision."